The present invention concerns a hermetic coaxial connector of the type intended to be fixed to a panel to ensure hermetic coaxial traverse of said panel.
Such coaxial connectors comprise a conductive central contact housed with interposition of an insulator in a housing that forms an outside conductor provided with means of attachment to a panel, a sealing joint between said housing and the panel, and a sealing device between the central contact and the outside conductor of the connector.
In connectors of a first type, those with so-called direct sealing, the sealing device is a glass bead that is directly sealed to the central contact and external housing. These connectors present the drawback of being too high in price because of the need to choose a material capable of sealing for the housing, such as ferronickel for example.
The housing so produced is fragile and can readily deteriorate during installation and/or disassembly of the connector on the corresponding panel, especially when the connector is of the screw type.
Moreover, because the housing is sealed by the glass bead to the central contact, it is not possible to replace merely the external conductor in the event of damage.
In addition, in this type of connector with direct sealing the sealing operation proper is relatively complex, requiring the use of graphite positioners that match the shapes of the external housing, the glass bead and the central contact.
The manufacturing cost of such connectors is therefore also high.
Another type of connector is also known, the so called mounted bead type, whose sealing device comprises an insulating glass bead sealed to the central contact and to an annular ring housed in a recess of the housing and attached to the latter by low temperature soldering.
Relative to the first type of connector mentioned above, the mounted bead connectors offer the advantage of using more conventional materials for the housing and thus materials of lower cost.
A very important drawback, on the other hand, resides in the need for a soldering operation which must be carried out at low temperature at about 200.degree. C. in order to avoid degradation of sealing. For this soldering operation it is necessary to carry out preparation of the surface of the housing, which is a delicate operation that is difficult to automate and requires precise handling which leads to increased cost. Moreover, there are risks of appearance of a leakage path at the level of the soldering, which reduces the reliability of the connector.
In addition, as in the first type of connector with direct sealing, it is not possible because of soldering to replace the external conductor without replacing the entire connector in the event of damage.
The present invention proposes to provide a hermetic coaxial connector that precisely avoids the drawbacks of the previous connectors just mentioned, avoiding in particular the use of costly and fragile materials for the external housing, requiring no soldering operation on the housing and offering the advantage of permitting replacement of the housing without replacing other elements of the connector, if necessary.
The connector according to the invention comprises an insulating glass bead sealed to the central contact and to an annular ring housed at least partly in a recess of the housing, and is essentially characterized by the fact that said ring presents a staggered configuration containing an axial annular span connected via the glass sealing bead to the central contact, an axial span in contact with a corresponding span of the housing, a first radial span resting against a corresponding span of the housing and a second radial span in contact with the sealing joint interposed between the ring and panel.
One understands that the structure of the staggered ring according to the invention is in no way integral with the housing forming the external conductor, which permits easy changing of the latter in the event of damage.
Conventionally, the connectors according to the invention can be mounted by screwing them in a bore having a top and a bottom provided for this purpose in a panel, the housing forming the external conductor presenting for this purpose a threading, in which case the ring advantageously presents according to the invention a section of reduced diameter having a radial end span placed against a corresponding span of the bottom of the bore, the sealing joint being housed in a space defined by the bore of the panel, said section of reduced diameter of the ring and said second radial span of the ring forming the contact with the sealing joint.
As a variant the connectors according to the invention can present a collar attachment, in which case according to the invention one carries out installation of the ring integral with the bead in a corresponding recess of the external conductive housing, the sealing joint being housed in a space defined by the panel, the ring and the annular axial internal span of the collar.
Other characteristic advantages of the invention will appear on reading the following specification with reference to the accompanying drawing in which: